Aerothermodynamics Overview and Prediction Assessment · 2013-04-10 · Aerothermodynamics Overview and Prediction Assessment Dr. James D. Heidmann Aerothermodynamics API Subsonic

Aerothermodynamics Overview and Prediction Assessment

Dr. James D. Heidmann Aerothermodynamics API

Subsonic Fixed Wing Project

Fundamental Aeronautics Annual Meeting New Orleans, LA October 31, 2007

An overview of the Aerothermodynamics Discipline within NASA’s Subsonic Fixed Wing Project is given. The primary focus of the presentation is on the research efforts conducted in fiscal year 2007. This year (2007), the work primarily consisted of efforts under level 1 (foundational research) and level 2 (tools and technology development). Examples of work under level 1 are large eddy simulation development, advanced turbine cooling concept development, and turbomachinery flow control development. Examples of level 2 research are the development of highly-loaded compressor and turbine test programs and advanced turbomachinery simulation development, including coupled inlet-fan simulations. An overview of the NRA research activity is also provided. This NRA focused on plasma and aspiration flow control for low pressure turbine application. Finally, a status report on the turbomachinery CFD code assessment activity is provided. This activity focuses on the use of several NASA in-house codes for the NASA rotor 37 and stage 35 test cases.

https://ntrs.nasa.gov/search.jsp?R=20080005556 2020-04-08T21:02:30+00:00Z

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National Aeronautics and Space Administration

www.nasa.gov

Aerothermodynamics Overview and Prediction Assessment

Dr. James D. HeidmannAerothermodynamics API

Subsonic Fixed Wing Project

Fundamental Aeronautics Annual MeetingNew Orleans, LAOctober 31, 2007

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Outline

• Aerothermodynamics Overview

• In-House Research Progress

• Turbomachinery Code Assessment

• NRA Research Progress

• Summary

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Aerothermodynamics Research Objectives

• Develop fundamental understanding and enabling technologies required for concepts such as ultra-high bypass engines, high power density cores, and embedded engines for hybrid wing vehicles.

• Dramatically improve engine thermal efficiency, reduce fuel burnand emissions, and reduce weight and complexity of engine systems.

• Improve understanding through experimental and analytical study of engine inlets, fans, compressors, turbines, and nozzlesand their interactions.

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Aerothermodynamics Research Impact on Fuel Burn

N+1 Conventional Small Twin• 162 pax, 2940 nm mission baseline

• Ultra high bypass ratio geared engines

• High power density engine cores

• Key Aerothermodynamics technology targets:

+1 point increase in turbomachinery efficiencies

-25% reduction in turbine cooling

+50 deg. F compressor temperatures (T3)

+100 deg. F turbine rotor inlet temperatures

Fuel Burn = 39,300 lbs1998 EIS Technology

-8400 lbs (-21%)

Aerodynamic Improvements∆∆∆∆ Fuel Burn = - 1.5%

Fuel Burn = 30,900 lbs

Advanced Materials and Structures∆∆∆∆ Fuel Burn = - 5%

Advanced Propulsion∆∆∆∆ Fuel Burn = - 15%

Subsystem Improvements∆∆∆∆ Fuel Burn < 0.5%

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Integrated Embedded Propulsion Systems

N+2 Hybrid Wing/Bodywith Embedded Engines

Distorted inlet flow propagated to fan-face forhybrid wing vehicle embedded engine, highlighting

challenges in fan design and operation.

NRA Round 2 Addresses Embedded Propulsion Issues

Noise and fuel burn benefits to embedded

engines

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Aerothermodynamics Research Areas:

• NRA Cooperative Agreements & Contracts

• Foundational Research: • Model and Method Development• Flow Control Development• Cooling Concept Development

• Technologies & Tool Development• Turbomachinery Simulation Development• Advanced Compression System Development• Advanced Cooled Turbine Development• Advanced Inlet and Nozzle Development• Turbomachinery Code Assessment

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Foundational Research: Model and Method Development

LES simulation of vortex interaction for a ducted propeller. Interactions between tip clearance

vortex, shed vortex and tip vortex from the

adjacent blade produce low pressure area. Tip

gap size affects this phenomena.

T.E. vortex shedding

Blockage due to vortex merge

Low pressure

area

Large Eddy Simulation of Vortex Interactions at 95 % Span

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Foundational Research: Flow Control Development

B-B

A-A

A A

B B

FLOW

X

Z

Experimental Study on Flow Control over a Blade by Acoustic Excitation (Synthetic Jets)

Typical Stator Wake Loss Reductionas a Function of Increas ing Mom entum Coeff icient

Synthetic Jet in Axial Com pr essor s tator b lade

-25.0%

-20.0%

-15.0%

-10.0%

-5.0%

0.0%

0.000000 0.002000 0.004000 0.006000 0.008000 0.010000 0.012000

M o ment um C o ef f i c i ent

Typical Stator Wake Loss ReductionAs a Function of Increasing Momentum

Coefficient for a Synthetic Jet in anAxial Compressor Stator Blade

Momentum Coefficient

Lo

ss R

edu

ctio

n

10% to 20% reduction in aerodynamic loss achieved with

zero net mass flow devices

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Foundational Research: Cooling Concept Development

Comparison of round hole and “ anti-vortex”turbine film cooling jet attachment

Typical film cooling jet lift-off behavior

Side view Front view

Flow Direction

“ Anti-vortex” film cooling concept

Round hole Anti-vortex holeTop view

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Technologies & Tool Development:Turbomachinery Simulation Development

Axial Compressor with discrete flow injection to mitigate rotating stall

88

90

92

94

96

98

100

0 60 120 180 240 300 360

Normalized distortion sector

Per

cen

t su

rge

exit

pre

ssu

re r

ise zeta = 0.25, om = 0, twin swirl

zeta = 0.5, om = 0., twin swirl

zeta = 0.25, om = 0.8, no swirl



Swirl distortion

Total pressure distortion

Impact of twin-swirl and total-pressure circumferential distortions

Model for static & dynamic response of fans & compressors to inlet total

pressure & swirl distortion developed using harmonic balance technique

Integrated inlet/fan simulations with inlet flow distortion and flutter

condition complete using TURBO.

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Technologies & Tool Development:Advanced Compression System Development

21 Blade Row High Pressure CompressorAnalysis with APNASA Code

NASA Glenn W7 compressor facility currently being

upgraded to full multistage testing capability

Initial test article is 76B 3-stage compressor

Advanced highly-loaded 3-stage compressor testing

proposed

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Technologies & Tool Development:Advanced Cooled Turbine Development

General Electric Highly-Loaded High Pressure Turbine

Both High and Low Pressure Turbines to be Tested in NASAGlenn Single Spool Turbine Facility (W6)

Conventional Reduced Shock Design

Pressure Ratio = 3.25

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Technologies & Tool Development:Advanced Inlet and Nozzle Development

Subsonic scarf-inlet designs with inletlength transition angles of 180° and 67.5°.

Versatile Integrated InletPropulsion Aerodynamics Rig Fan Exit Probes

Rotating AIP Rake Fan Exit RakesInstrumented IGV’s

Research focuses on inlet/fan interaction

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Technologies & Tool Development:Turbomachinery Code Assessment

• Code assessment conducted for 5 NASA turbomachinery Navier-Stokes CFD codes• Glenn-HT – Convective Heat Transfer Focus• H3D – Large Eddy Simulation Capability• Swift – Mixing Plane• APNASA – Average Passage Modeling• TURBO – Full Unsteady Simulation

• Test cases chosen based on previous benchmark activity, availability of high quality validation data, and relevance of case• NASA Rotor 37 – transonic compressor with very high quality data• NASA Stage 35 – transonic compressor stage for interaction effects

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H3D Analysis for NASA Rotor 37

Relative Mach Number

New analyses at near-stall condition performed using recently-developed large

eddy simulation (LES) capability.

Instantaneous Mach number distribution at 90% span.

Mass flow rate slightly higher than peak efficiency.

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SWIFT Analysis for NASA Stage 35

18 19 20 21 22MASS FLOW [KG/SEC]

1.70

1.75

1.80

1.85

1.90

1.95

2.00

TO

TA

L P

RE

SS

UR

E R

AT

IO

STAGE 35DATASWIFT


1.15

1.20

1.25

1.30

TE

MP

. RA

TIO


0.60

0.70

0.80

0.90

1.00

EF

FIC

IEN

CY

Relative Mach Number

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APNASA Analysis for Rotor 37

Effect of Hub Leakage on Total Pressure Profiles

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TURBO Analysis for Stage 35

36 rotors 46 stators

67 million grid points

TURBO prediction of stall inception

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Stage 35 with Tip Injection

TURBO Analysis for NASA Stage 35

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Aerothermodynamics NRA Investment

6 Round 1 NRAs awarded – starting Jan 2007

AshpisPlasma ActuatorsHershkowitzUniv. Wisconsin

PoinsattePlasma Flow ControlT. SimonUniv. Minnesota

AshpisPlasma ActuatorsMilesPrinceton Univ.

StrasizarLPT Flow ControlBonsOhio State Univ.

StrasizarLPT flow ControlVolinoNaval Academy

HahTurbulence ModelingDurbinIowa State Univ.

Tech. Monitor

Topic AreaPIUniversity

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Aerothermodynamics NRA Investment

3 Round 2 NRAs awarded – starting October 2007

Integrated Embedded Propulsion Systems (N+2)

ArendInlet/Fan InteractionFloreaUnited Technologies

AbbottInlet Flow ControlMaceThe Boeing Company

HathawayHigh Fidelity ModelingWhitfieldU. of Tennessee-Chatt.

Tech. Monitor

Topic AreaPIPerformingOrganization

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INSULATOR

ELECTRODE

ELECTRODE

DBD PLASMA

��

��

��

��

�

�

��

��

��

��

ω�

Dielectric Barrier Discharge (DBD) Plasma ActuatorsAdvantages of a GDP actuators• Pure solid state device

• Simple, no moving parts• Flexible operation, good for

varying operating conditions

• Low power• Heat resistance – w/ proper

materials

��

��!"��#��$

Background

APPLIED VOLTAGE

“WIND”

��

��!%�� &'$

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The customary approach to DBD actuators:• The applied voltage is in AC voltage 5-80 KV • Signal shape: sine wave , saw-tooth, etc • Frequency range 2-20 KHz.• Generated “wind” peak velocities obtained 1-20 m/s

The Princeton novel approach to DBD actuators:• Applied voltage: Ultra short pulses – nanoseconds• Repetition rate > 100 KHz • Bias Voltage• Predicted two orders magnitude increase in “wind”

peak velocities

Approach• Computational• Experimental

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Example computational case: high voltage repetitive short negative Gaussian pulses and dc bias•Peak voltage: -4.5 kV, FWHM: 4 ns, Bias: 0.5 kV, f=500kHz

electrons

positive ions

electricpotential

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Example computational case: high voltage repetitive short positive Gaussian pulses and dc bias

•Peak voltage: 3 kV, FWHM: 4 ns, Bias: 1 kV, f=500kHz

electrons

positive ions

electricpotential

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Experimental setup

Dielectric material:kapton tapethickness 100 m

Electrodes:copper foilwidth 25 mmspanwise dim. 50 mm

The circuit is designed so as to superimpose short pulses on a low frequency bias voltage without interference between the pulser and the low-frequency power supply. The pulses and the bias voltage are controlled independently

Pulse

Bias

combinedsignal

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Schlieren techniquefor the DBD plasma actuator induced flow

Schlieren technique, burst mode of plasma actuator operation, and 2-D fluid numerical model coupled together allow to restore the entire two-dimensional unsteady plasma induced flow pattern as well as the characteristics of the plasma induced force.

(!)�*��+,��,�*��-��.

Numerical modeling

Schlieren visualization

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Induced Momentum – via force measurements

2.7 5.3 8.0 10.7

10

20

30

40

Force, mN/m

Bias Voltage, p-to-p, kVP

RR

, kH

z

0

1.500

3.000

4.500

6.000

7.500

9.000

10.50

12.00

MACOR 1/16’’Negative pulses 5kV

0 10 20 30 40 50

0

1

2

3

4

5

6

7

8

9

10

11

12

Bias Voltage, p-to-p, kV

For

ce, m

N/m

PRR, kHz

1.4 2.7 4.0 5.3 6.7 8.0 9.3 10.7 11.0

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Princeton NRA Summary

• Progress has been made in deriving significantinsights into the effect of the applied voltage and the role of the bias voltage.

• The discharge is efficiently controlled by ultra-short pulsing,• Gas acceleration is controlled by the bias voltage• The effects can be controlled independently

• Progress has been made in further development of the numerical code – algorithm and parallelization

• Numerical simulation already provided clear guidance for experiments. • Experiments point to needed code improvements

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Aerothermodynamics Summary

• Aerothermodynamics technologies play a critical role in the Subsonic Fixed Wing Project goals, particularly with respect to performance and fuel burn.

•NASA in-house efforts making progress in both foundational research and technology & tool development.

•Turbomachinery code assessment activity progressing with latest tools for NASA rotor 37 and stage 35.

•Significant investment in external research through NRA rounds 1 & 2

•Round 1 focus on flow control•Round 2 focus on embedded engine issues

Documents

Aerothermodynamics Overview and Prediction Assessment · 2013-04-10 · Aerothermodynamics Overview and Prediction Assessment Dr. James D. Heidmann Aerothermodynamics API Subsonic